KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 145 



Forma arctica. Stauros narrow. Strife 19 to 21 in 0,oi mm. — S. pcllucida Cl. Vega 

 p. 47.5 Pl. XXXV f. 10. 



Marine: Cape Wankarema (Noi'th Siberian Sea)! 



Forma mediterranea. Stauros broad, irregularly subqnadrate. Strife 16 in 0,oi mm. 



Marine: Barcelona! Balearic Islands! 



This is a curious form, not closely connected with any other known species, so tbat its 

 position in a natural system is uncertain. I have placed it liei'e only provisionally. It always 

 occurs very sparinglj'. 



2. S. (Libellus) constricta (Ehb. 184,3?), W. Sm. (1853). — V. membranaceous, linear, 

 convex, sometimes constricted in tbe middle, witli snbacute, ronnded or subcnneate ends. L. 0,0 5 to 

 0.14; B. 0,0 7.') mm. Stauros pervious, narrow linear. Axial area indistinct. Strife 25 to 27 in 

 0,01 mm. transverse. Frustule witb complex connecting zoiie. — Sfaurou. constricta Ehb. Am. 

 Pl. I: 2 f. 12 b.? Äm.phiprora constricta W. Sm. B. D. I Pl. XV f. 126. Staitron. amjjhoroides 

 Grun. in A. S. Atl. XXVI f. 35 to 39. Åar. shmdans Donk. B. I), p. 60 Pl. IX f. 3 (1873)? 



Marine or brackisli: Davis Strait! North Sea (coasts of Sweden, England, Normandy)! 

 Adriatic (flrun.). 



It is not very probable tliat St. constricta of Ehrenberg represents this species, whatever 

 it may be. 



3. S. (Llbellus) Biblos Cl. (1892). — V. thin and very convex, linear-elliptical with obtuse 

 ends. L. 0,o5 5; B. 0,015 mm. Central pores approximate. Central nodule transversely dilated 

 into a narrow stauros. Terminal nodules distant from the ends of tbe valve. Strife about 30 in 

 0,01 mm. composed of fine puncta somewhat less close, forming undulating, longitudinal rows. 

 Frustule quadrate. Zone broad, with nnmerous longitudinal divi.sions. — Cl. Diatomiste I p. 77 

 Pl. XII f. 9, 10. 



Marine (pelagic): Barbados! 



This species is of interest as it bas a very complex connecting zone and at tbe same time 

 a well developed stauros. Tbe former characteristic as well as tbe sculpture of tbe valve and tbe 

 distant terminal nodules, prove that it is nearly akin to Å\ rJiomhica. Tbe latter characteristic 

 shews an aflfinity to Stauroneis salina. 



4. S. (Libellns) africana Cl. (1881). — V. lanceolate, with subacute ends, convex. L. 0,05 

 to 0,0 6; B. 0,0) to 0,01.3 mm. Stauros narrow, pervious. Strife 23 in 0, 01 mm. transverse. Con- 

 necting zone with faint longitudinal divisions. — Cl. N. R. D. p. 15 Pl. III f. 42. 



Brackish water: South Africa! Ceylon (Weissflog Coll.)! 



Var. acuminata Grun. — V. acuniinate. Striee 23 in 0,oi mm. Grun. in V. H. T. N:o 137. 

 Marine: Norfolk. 



This species is intermediate between S. constricta and S. salina, having the fine .strife of the 

 former and the form of the latter. It is more silicious than S. constricta. 



5. S. salina W. Sm. (1853). — V. lanceolate, with subacute ends. L. O.os to 0,08; B. 0,012 

 to 0.0 14 mm. Axial area indistinct. Stauros narrow, slightly dilated towards the margins, pervious. 

 Strife 17 to 18 in 0,oi mm. transverse, finely punctate. — W. Sm. B. D. I p. 60 Pl. XIX f. 188. 

 V. H. Syn. p. 68 Pl. X f. 16. Lägst. Bob. D. p. 47 f. 5. 



Marine: North Sea! Mediterranean Sea (Balearic Islands)! Black Sea (Sebastopol) ! 

 Var.? latior Daxnf. (1882). — V. broadly lanceolate, with rostrate ends. Striaj? — Dannf. 

 Balt. D. p. 32 Pl. III f. 21. 



Brackish water: Baltic, Bay of Finland (Dannf.). 



6. S. Gregorii Ralfs (1861). — V. lanceolate, gradually tapering from the middle to the 

 obtuse ends. L. 0, 05 to 0,i; B. 0, 01 to 0,01.3 mm. Stauros broad, pervious. Strife 16 to 20 in 



K. Sv. Vet. Akad. Handl. Baud 26. N;o 2. 19 



